1. Field of the Invention
The present invention relates to the field of display technology, and in particular to a method for manufacturing a flexible graphene electrically conductive film.
2. The Related Arts
A transparent electrically conductive film is a necessary functional material for liquid crystal displays (LCDs) and touch panels (TPs). Existing electrically conductive films that involve mature arts and have excellent performances are primarily metal films and metal oxide films. Indium tin oxide (ITO) films have excellent optical and electrical properties and are thus widely used in the display industry. However, sputtering of ITO films must be carried out in a high temperature and involves pillar like microscopic structure, leading to constraint of its application to low-temperature or room-temperature coatings of flexible bases thereby greatly constraining the progress of flexible display technology. Thus, it is a trend of development to seek for a material that has high electrical conductivity, flexibility and transparency, and low cost for substitute of ITO. With the emergence of graphene that is two-dimensional material, the excellent electrical property and good light transmittance thereof attract wide attention of people. Further, graphene possesses certain features, such as atomic-grade thickness in a vertical direction, atomic-grade levelness, surface inactiveness, and zero trap state and is regarded as the most promising material as a substitute of ITO, and is now a hot spot of international research and study in the display field.
Applying chemical vapor deposition (CVD) to grow graphene on a surface of a base made of metals such as copper is the primary way of obtaining high-quality layer-controllable graphene and such a process has already achieved growth in a large scale for large areas, making a first move toward practical application of graphene as substitute of ITO. However, in the process of practical application, one major problem is to transfer CVD manufactured graphene to a target backing. The most mature state of the art is the so-called PMMA (poly methyl methacrylate) assisted process, wherein a PMMA membrane is taken as a support on a surface of graphene and a copper etchant is applied to etch away and remove metal copper. Then, graphene is transferred to the surface of the backing and finally, the PMMA membrane on the surface of graphene is removed through dissolution. It is noted that due to the strong attachability of the graphene surface and also the limited dissolubility of the PMMA polymer in an organic solvent, it is easy to cause residues of PMMA left on the graphene surface, leading to negative influence on the electrical property of graphene. Further, the organic solvent, which is generally acetone, cannot be repeatedly reused to remove PMMA and this would cause a great burden to the environment.